I am relocating an upstairs vanity sink from one wall to another (also going from single to double bowl). Rather than relocate the drain and vent pipe, I am hoping that I can tie into a 1-1/2" copper vent pipe that is located right behind the vanities intended location. The copper vent pipe is from a dedicated vent/drain that runs from below the concrete slab in my basement up through the roof. The vent/drain serves my kitchen sink and dishwasher. From what I can tell, the pipe runs vertical for the entire run and the kitchen/dishwasher is branched off of this main vertical stack.

Is it permissible for me to tie directly into this vent/drain pipe? If so, I assume that I have to run an 1-1/2" horizontal drain line from the sinks to the main stack and add a vent line above the sink drains tying back into the main stack.
What are the correct fittings to accomplish this?
Are there any simple images/links you can provide to help answer these questions?

Thanks for any insight you can provide.
tlyoung99

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The copper vent pipe is from a dedicated vent/drain that runs from below the concrete slab in my basement up through the roof. The vent/drain serves my kitchen sink and dishwasher. Is it permissible for me to tie directly into this vent/drain pipe? If so, I assume that I have to run an 1-1/2" horizontal drain line from the sinks to the main stack and add a vent line above the sink drains tying back into the main stack.

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To tie your vanity drain back to that copper vent you would have to cut in a vent for the kitchen and run it up 6" over the flood rim of your vanity and then revent back into the copper vent.
Good luck, Tom PS. Sorry for the delay in answering.